As a conventional image forming device that employs an electrophotographic system, there is known a printer provided with a photosensitive member, and a developer cartridge that supplies toner to the photosensitive member.
As an example of a developing cartridge provided in this type of printer, there is known a developing cartridge having a casing that includes: a toner accommodating chamber configured to accommodate toner and provided with an agitator for agitating the toner; and a developing chamber supporting a developing roller and a supply roller (see Japanese Patent Application Publication no. 2012-53095, for example).
In this developing cartridge, driving force from a main casing is configured to be transmitted from a receiving gear for receiving the driving force, via an intermediate gear engaging the receiving gear, to an agitator gear for driving the agitator.